selftests/vm: use memfd for hugetlb-madvise test

For dropping the hugetlb mountpoint in run_vmtests.sh.  Since no parameter
is needed, drop USAGE too.

Link: https://lkml.kernel.org/r/20221014143921.93887-3-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/vm/hugetlb-madvise.c

@@ -12,6 +12,7 @@
  * directory.
  */
 
+#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -19,7 +20,6 @@
 #define __USE_GNU
 #include <fcntl.h>
 
-#define USAGE	"USAGE: %s <hugepagefile_name>\n"
 #define MIN_FREE_PAGES	20
 #define NR_HUGE_PAGES	10	/* common number of pages to map/allocate */
 
@@ -103,11 +103,6 @@ int main(int argc, char **argv)
 	int fd;
 	int ret;
 
-	if (argc != 2) {
-		printf(USAGE, argv[0]);
-		exit(1);
-	}
-
 	huge_page_size = default_huge_page_size();
 	if (!huge_page_size) {
 		printf("Unable to determine huge page size, exiting!\n");
@@ -125,9 +120,9 @@ int main(int argc, char **argv)
 		exit(1);
 	}
 
-	fd = open(argv[1], O_CREAT | O_RDWR, 0755);
+	fd = memfd_create(argv[0], MFD_HUGETLB);
 	if (fd < 0) {
-		perror("Open failed");
+		perror("memfd_create() failed");
 		exit(1);
 	}
 
@@ -406,6 +401,5 @@ int main(int argc, char **argv)
 	(void)munmap(addr2, NR_HUGE_PAGES * huge_page_size);
 
 	close(fd);
-	unlink(argv[1]);
 	return 0;
 }